Method and device for the production of alkylates

ABSTRACT

Disclosed is a device for the production of alkylate(s) by sulfuric acid alkylation of at least one isoparaffin such as isobutane with at least one olefin, such as butylenes. The device includes a mixing chamber for preparing a mixture of the isoparaffin with recycled reaction products. It also includes an emulsion chamber for preparing a first hydrocarbons-in-sulfuric acid emulsion, where the mixture prepared in the mixing chamber is injected in multiple parallel jets into a sulfuric acid composition. The device further includes a pre-reaction chamber for preparing a second emulsion, where a given portion of the olefin is injected in jet streams into the first hydrocarbons-in-sulfuric acid emulsion coming from the emulsion chamber. Last of all, the device includes a reaction chamber of given height and cross-section where the second emulsion coming from the pre-reaction chamber is injected through nozzles and another portion of olefin is injected in jet streams all over the cross-section and height of the reaction chamber. The reaction chamber is devised so that the second emulsion is circulated in a closed circuit and it has an outlet through which a balanced amount of reaction mixture is continuously discharged. All of said mixing chamber, emulsion chamber, pre-reaction chamber and reaction chamber are coaxially arranged one above the other in vertical position and altogether form a reactor with the prechamber being located at the bottom of the reactor and the reaction chamber on top thereof. A method for the production of alkylates by means of the above device is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of U.S. application Ser. No.10/297,205, filed Dec. 4, 2002, which is based upon PCT National StageApplication No. PCT/IB01/00962 filed Jun. 1, 2001, and claims thebenefit of priority from prior Canadian Patent Application Nos.2,310,858, filed Jun. 6, 2000, the entire contents of which areincorporated herein by reference.

INVENTION BACKGROUND

1. Field of the Invention

The present invention relates to a method for the production ofalkylates by sulfuric acid alkylation of isoparaffins with olefins. Thismethod is particularly well adapted for use in the petroleum refiningindustry, using isobutane, as isoparaffin, and butylenes as olefin.

The invention also relates to a device for mixing and reacting at leasttwo and preferably three liquid components. This device is particularlywell adapted for carrying out the above method even though it can beused for carrying out many other methods.

2. Brief Description of the Prior Art

Alkylates are main components of high-octane motor fuels. They areproduced by alkylation of isoparaffins (mainly isobutane) by olefins(such as propylene, butylenes or amylenes) in the presence of sulfuricor hydrofluoric acid that serves as a process catalyst. The most widelyknown method for the production of alkylates in the petroleum refiningindustry consists of carrying out a sulfuric acid alkylation ofisobutane by olefin.

Numerous methods for carrying out sulfuric acid alkylation of isobutaneby olefins are known. The method according to the inventiondistinguishes over most of these known method in that the reaction iscarried out in a compact reactor which does not contain moving parts andin which jet mixing of the reagents is achieved.

U.S. Pat. No. 3,544,652 issued on Dec. 1, 1970 discloses a method forthe alkylation of isoparaffin by olefins in the presence of sulfuricacid, where the olefin is reacted with an alkylating hydrocarbon-in-acidemulsion formed by thoroughly mixing isoparaffin with sulfuric acidbefore contact with the olefin. In this patent, theisoparaffin-to-olefin volume ratio is disclosed as being equal to about12:1. The acid-to-hydrocarbons volume ratio is disclosed as being withinthe range of 2.5:1 to 15:1 but it is mainly maintained at about 6:1. Thereaction is carried out adiabatically, mainly in a continuous manner, ina reactor called “alkylation contactor”, which is provided with a mixerthat is devised for forming the isoparaffin-in-sulfuric acid emulsionand for thoroughly and homogeneously mixing the so-formed emulsion withthe olefin at the points of delivery of the latter into the reactor.

As the liquid flows through the reactor, the temperature of thealkylating mixture rises continuously by 5 to 15° C., thereby reducingviscosity of the mixture and increasing its turbulence. The method iscarried out at a temperature of 5 to 60° C. under a pressure sufficientfor keeping the reagents in a liquid state (from 2 to 10 ATMs). Prior tobeing mixed with the isoparaffin, sulfuric acid at a concentration of 88to 99% is cooled down to a temperature of about 4° C.

The emulsion preparation and the olefin injection and distributioninside the reaction area are not disclosed in detail in this U.S.patent.

The method disclosed in U.S. Pat. No. 3,544,652 is efficient but itrequires a substantial amount of power for circulating the acid due tothe very high acid-to-hydrocarbons ratio. It also requires a settlingequipment of a very large size. Moreover, the method disclosed in thispatent cannot guarantee a low consumption of sulfuric acid and areasonably high quality of the final product.

Russian patent No. 2,131,861 granted on Jul. 25, 1994 (corresponding toU.S. Pat. Nos. 5,443,799 and 5,777,189) discloses a method for sulfuricacid alkylation of isoparaffins by olefins and a device for carrying outthis method. At the initial stage of the method disclosed in thispatent, a thin isoparaffin-in-sulfuric acid emulsion is made byinjecting isoparaffin into an acid medium through a set of nozzles. Thenthe emulsion is delivered into a reaction area where olefin is fed,through a number of points normal to the emulsion flow. In this method,the alkylation is carried out under isobaric and isothermal conditions.

Russian patent No. 2,131,861 also discloses that the emulsion shouldpreferably flow in the emulsion area at a rate of 0.2 to 2 m/s—andwithin the reaction area at a rate of 0.04 to 0.27 m/s. Depending on theselected flow rate, the contact between the reagents may last from a fewto 60 seconds, thereby reducing to a minimum the possibility of notwanted side reactions such as oligomerization of olefins andautoalkylation of isoparaffins. Tests have shown that this methodpermits to prepare a thin unstable emulsion. Separation of the reactionmixture into a hydrocarbon phase and an acid phase takes 5 to 8 seconds,thereby allowing reduction in the setting time.

Since the method described in Russian patent No. 2,131,861 does notrequire rotary mixers, the equipment required for carrying it out israther cheap and of easy control and maintenance.

Russian patent No. 2,131,861 further discloses a device for carrying outthe above method. This device comprises a tank for preparing theemulsion. A special appliance is provided for isoparaffin injectionwithin the tank. Such an appliance essentially consists of a set ofaxially arranged nozzles. An appliance is also provided for sulfuricacid injection within the tank. The device also comprises a mixingchamber that is part of the tank, with an outlet throat, and acylindrical reactor which is connected in line to the throat of theemulsion preparation tank. To provide olefin injection, the devicecomprises a perforated branch pipe extending along the axis of thereactor.

The method and device described in the above Russian patent No.2,131,861 and its foreign counterparts have rather acceptable technicaland economic parameters of operations, as proved by industrial tests.However, those parameters could be improved if use is made of a higherlevel of flow turbulence in the reaction zone. In practice, such ahigher level of flow turbulence could be obtained if the flow rate isincreased in the reaction zone and the mixing conditions of olefin andemulsion flows are improved by using a more efficient olefin feed unitinstead of using a perforated branch pipe extending along the axis ofthe reactor.

Russian patent No. 2,092,475 granted on Dec. 6, 1995 is the closestprior art known to the Applicant. It discloses a method for theproduction of alkylates in a tubular reactor, which comprises mixingsulfuric acid with isobutane previously cooled down to a temperature ofnot over −2° C.; mixing the obtained emulsion with olefins alsopreviously cooled to a temperature of not over −2° C., in a plurality ofstages; separating the sulfuric acid from the obtained reaction mass;and recycling it. This method requests that the sulfuric acid be mixedwith the isobutane and the obtained emulsion be mixed with the olefin inan injector-type mixer, with an isobutane-to-sulfuric acid injectionratio of 3.3 to 5.2 and an isobutane-to-olefin volume ratio of3000-5000:1. In this method, sulfuric acid is separated from thereaction mass in a hydrocyclone.

Russian patent No. 2,092,475 also discloses a device for carrying outthe above method, which consists of a reactor provided with threeconcatenated injection mixers. Each mixer is provided with an olefininjection appliance that distributes the feed in a helical fashion alongthe length of a device.

With the method and device disclosed in Russian patent No. 2,092,475,one may carry out sulfuric acid alkylation of isoparaffins by olefins ina compact reactor that has no moving parts. One may also obtain a highquality alkylate, as proved by industrial tests. However, in practice,an isobutane-to-olefin ratio of 3,000-5,000:1 can be obtained in thereaction area only with very high power consumption. Alkylate qualityand specific sulfuric acid consumption could actually be improved byusing a more efficient olefin feed unit than the perforated tube withhelical openings as described in this patent. Besides, alkylate qualityand specific sulfuric acid consumption could be improved by optimizationof the alkylation process conditions, by proper selection of differentsize ratios of the reactor elements and by an improved process ofseparation of the reaction mixture and a device to carry out thisprocess.

OBJECTS AND SUMMARY OF THE INVENTION

A first object of the present invention is to provide a method for theproduction of alkylates by sulfuric acid alkylation of isoparaffins byolefins, which has the following advantages:

-   -   reduction in power consumption;    -   reduction in sulfuric acid consumption; and    -   improvement of the alkylate quality.

In accordance with the invention, this first object is achieved with amethod for the production of alkylate(s) by sulfuric acid alkylation ofat least one isoparaffin with at least one olefin, comprising the stepsof:

-   (a) preparing a mixture of said at least one isoparaffin with    recycled reaction products by mixing said at least one isoparaffin    previously cooled down to a temperature lower than +12° C. with    recycled reaction products separated from sulfuric acid and cooled    down to a temperature lower than +12° C.;-   (b) making a hydrocarbons-in-sulfuric acid emulsion by mixing    sulfuric acid with the mixture obtained in step (a);-   (c) preparing another emulsion by injecting a given portion of said    at least one olefin in jet streams through nozzles into the    hydrocarbons-in-sulfuric acid emulsion obtained in step (b);-   (d) injecting the other emulsion obtained in step (c) through    nozzles into a reaction chamber of given height and cross-section,    where said other emulsion is circulated in a dosed circuit and a    corresponding amount of reaction mixture is continuously discharged;-   (e) injecting another portion of the said at least one olefin in jet    streams into the other emulsion through a system of injectors    distributed in the reaction chamber all over the cross-section and    height of said reaction chamber; (f) processing the reaction mixture    discharged from the reaction chamber through at least one    hydrocyclone in order to separate said reaction mixture into an    acid-containing phase and an hydrocarbon-containing phase, and    subjecting each of said phases to a pressure reduction and a gas    separation;-   (g) recycling to step (a) one part of the hydrocarbon-containing    phase that is in a liquid form after said gas separation, said    recycled part acting as said recycled reaction products, recovering    the remaining part of the hydrocarbon-containing phase and    subjecting said recovered part to deacidification, purification and    separation to extract the requested alkylate(s); and-   (h) recycling to step (b) the acid-containing phase after said gas    separation and a cooling, said recycled acid-containing phase acting    as said sulfuric acid composition, part of said acid-containing    phase being withdrawn to regeneration prior to being recycled and    being replaced by fresh acid.

In accordance with a preferred embodiment of the invention, thepreparation of the emulsion and the alkylation process carried out insteps (a) to (d) are run in vertical flows.

In accordance with another preferred embodiment of the invention, steps(b) and (h) are controlled in such a manner that the amount of sulfuricadd circulating through the reaction chamber and processed in step (f)ranges from 40 to 80 m³ per ton of commercial grade alkylate.

Preferably also, steps (b) and (d) are controlled in such a manner thatin step (b), the first emulsion flows at a rate of 1.5 to 3.5 m/s and instep (d), the second emulsion flows in the reaction chamber at a rate of2 to 4 m/s.

Further preferably, steps (c) and (d) are controlled in such a mannerthat said at least one olefin be injected with a pressure drop higherthan 1 kg/cm².

The above method for the production of alkylate(s) by sulfuric acidalkylation of isoparaffin(s) by olefin(s) is quite efficient andecologically safe. The number of pieces of equipment as well as thequantity of explosive, toxic and corrosive substances needed to operatethe unit are dramatically reduced, such reduction being achieved notonly by a lower time of reaction and a reaction chamber of smallervolume, but also by a lower time of separation of the reaction mixturein the hydrocyclone(s). Also reduced are the electric power consumption,the size required for the unit site, the man-hours, etc. Furthermore,the overhaul life of the device is dramatically increased, therebyresulting in a reduction in production losses. Leakage of variousproducts in the environment is also dramatically reduced.

The method according to the invention also permits to obtain asubstantial reduction in power and sulfuric acid consumption. It furtherpermits to improve the alkylate quality.

A second object of the present invention is to provide a device that isdesigned, in particular, for running the process of sulfuric acidalkylation of isoparaffin by olefins. This device can also be used forcarrying out a great number of other processes that require thoroughmixing of several liquid components and creation of suitable conditionsfor their interaction.

In accordance with the invention, this second object is achieved with adevice for mixing and reacting at least two liquid components,comprising:

-   (a) a mixing chamber for preparing a mixture of two of said    components;-   (b) an emulsion chamber for preparing a first emulsion, where the    mixture prepared in the mixing chamber (a) is injected in multiple    parallel jets;-   (c) a pre-reaction chamber for preparing a second emulsion, where a    given portion of one of said components is injected in jet streams    into the first emulsion coming from the emulsion chamber (b); and-   (d) a reaction chamber of given height and cross-section where the    second emulsion coming from the pre-reaction chamber (c) is injected    through nozzles and one of the components is injected in jet streams    all over the cross-section and height of said reaction chamber, said    reaction chamber being devised so that said second emulsion is    circulated in a closed circuit and comprising an outlet through    which a balanced amount of reaction mixture is continuously    discharged;    wherein the mixing chamber (a), emulsion chamber (b), pre-reaction    chamber (c) and reaction chamber (d) are coaxially arranged one    above the other in vertical position and altogether form a reactor    with the mixing chamber (a) being located at the bottom of the    reactor and the reaction chamber (d) on top thereof.

When used for the production of alkylate(s), the above device morespecifically comprises:

-   (a) mixing chamber for preparing a mixture of said at least one    isoparaffin with recycled reaction products;-   (b) an emulsion chamber for preparing a first    hydrocarbon-in-sulfuric acid emulsion by mixing sulfuric acid with    the mixture prepared in the mixing chamber (a);-   (c) a pre-reaction chamber for preparing a second emulsion, where a    given portion of said at least one olefin is injected in jet streams    into the first hydrocarbons-in-sulfuric acid emulsion coming from    the emulsion chamber (b); and-   (d) a reaction chamber of given height and cross-section where the    second emulsion coming from the pre-reaction chamber (c) is injected    through nozzles and another portion of the at least one olefin is    injected in jet streams all over the cross-section and height of the    reaction chamber,    wherein the mixing chamber (a), emulsion chamber (b), pre-reaction    chamber (c) and reaction chamber (d) are coaxially arranged one    above the other in vertical position and altogether form a reactor    with the mixing chamber (a) being located at the bottom of the    reactor and the reaction chamber (d) on top thereof.

A third object of the present invention is to provide a method forseparating into phases the reaction mixture exiting from the above unitof sulfuric acid alkylation of at least one isoparaffin by at least oneolefin, the phases including a liquid hydrocarbon-containing phase and aliquid acid-containing phase. This method has for the followingadvantages:

-   -   alkylate quality improvement;    -   reduction of sulfuric acid consumption;    -   reduction of ethers other acid compounds in liquid reaction        products; and    -   reduction of acid compounds in vapor phase.

In accordance with the invention, this third object is achieved by amethod which comprises the steps of:

-   -   Injecting the reaction mixture at a speed of 4 to 10 m/s into a        hydrocyclone in order to separate it into a liquid        hydrocarbon-containing phase and a liquid acid-containing phase;        and    -   further processing the phases by subjecting each of them to a        pressure reduction, injecting the phase having been subjected to        said pressure reduction into a gas separator, recovering liquids        from said gas separator by means of a pump for further        utilization, and extracting vapors from the separator by means        of a compressor.

In accordance with a first preferred embodiment of the invention, eachof the phases coming from the hydrocyclone and having been subjected topressure reduction, is fed into its own separator. Part of the liquidextracted from the hydrocarbon-containing phase separator is recycledfor mixing with isoparaffin in the process of alkylation of isoparaffinwith olefins, as described above. The remaining part of the liquid issubjected to rectification and fractionation to extract the requiredalkylate. On the other hand, the main part of the liquid extracted fromthe acid containing phase separator is recycled and mixed withisoparaffin and the recycled reaction products to prepare theacid-to-hydrocarbon emulsion, as described above. The remaining part ofthe sulfuric acid-containing phase flow is withdrawn for regenerationand replaced with an appropriate amount of make-up acid.

In accordance with another preferred embodiment of the invention, thephases withdrawn from the hydrocyclone and subjected to pressurereduction are fed to a common settling vessel separated by an overflowbaffle plate into a settling tank and an accumulation tank. Commercialgrade products are withdrawn from the accumulation tank forrectification and extraction of the requested alkylates. Acid iswithdrawn for recycling and regeneration from a lower part of thesettling tank, and the reaction products to be recycled are extractedfrom settling tank at a level that is lower than the upper end of theoverflow baffle plate of the settling vessel.

Advantageously, the hydrocarbon-containing phase can be subjected toanother separation in additional hydrocylone. After reduction and vaporextraction, the upper lightweight flow from the additional hydrocyclonecan be subjected to rectification and fractionation to extract therequested commercial grade alkylate while the lower heavy weight flowafter vapor extraction can be recycled to the reactor.

Advantageously also, the acid-containing phase can be subjected toanother separation in another additional hydrocyclone. The upperlightweight flow extracted from the additional hydrocyclone can berecycled while the lower heavy weight flow can be separated in yetanother additional hydrocyclone. The lower heavy weight flow from thelast hydrocyclone can be used as a second portion of acid to be recycledto the reactor while the upper lightweight flow can be withdrawn forregeneration.

A fourth and last object of the present invention is to provide a devicethat is designed, in particular, for separation of the reaction mixtureof the unit of sulfuric acid alkylation of isoparaffins by olefins intoliquid acid-containing and hydrocarbon-containing phases and a vaporphase. This device can be also used as a 3- or 4-phase separator inprocesses where vapor phase is withdrawn by a single flow while liquidphases are withdrawn in three separate flows. This device can be used,for example, as a 3-phase separator for the treatment of gas-saturatedand water containing oil where casing-head gas is withdrawn by a singleflow while oil and water are withdrawn by three separate flows. Forexample, dry oil can be withdrawn by a single flow while water can bewithdrawn by two separate flows. One flow is directed to afterpurification and subsequent pumping in an oil bed or pond dischargewherein another flow is directed to the head of the process for systemrecycling as a heat carrier or demineralizing agent.

In accordance with the invention, this fourth object is achieved with adevice for separating a reaction mixture containing immiscible liquidsof different densities and free gas or vapor, in such a manner as toobtain no less than three liquid flows and at least one gas or vaporflow. This device comprises a horizontal vessel incorporating:

-   (a) at least one vertical overflow baffle plate that extends within    said vessel and divides it into one settling tank and at least one    accumulation tank;-   (b) supply connecting pipes for introducing the reaction mixture    into the settling tank;-   (c) outlet connecting pipes for discharging the acid-containing    phase from a bottom portion of the settling tank;-   (d) other outlet connecting pipes for discharging the liquid    hydrocarbon phase in the form of two separate flows, one of said    flows being directed back to the unit for use as recycled reaction    products, the other one of said flows consisting of commercial grade    reaction products and being subjected to rectification and    fractionation in order to obtain commercial grade alkylates, wherein    the other outlet connecting pipes through which-the other one of the    flows exits from the vessel is located in a bottom portion of said    at least one accumulation tank; and-   (e) at least one further outlet connecting pipes for discharging the    vapor phase from an upper part of the vessel.

In accordance with a first preferred embodiment of the invention, theconnecting pipes used for withdrawal of the reaction products to berecycled is in the form of a perforated pipe header extending in thesettling tank at a given distance from the baffle plate, said pipeheader having an axis parallel to the overflow baffle plate andextending upwards at a given height from the bottom portion of saidsettling tank.

In accordance with another preferred embodiment of the invention, thevessel comprises two overflow baffle plates that divide the vessel intoone settling tank and two accumulating tanks. One of the accumulatingtanks is used for collecting the commercial grade reaction products andthe other accumulating tank is used for collecting the recycled reactionproducts. The settling tank can also be divided by another baffle plateof a given height into two settling sections for collecting commercialgrade products and recycled reaction products, respectively.

The invention and its advantages will be better understood upon readingthe following non-restrictive description of preferred embodimentsthereof made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a device for the production ofalkylate(s) according to a preferred embodiment of the invention;

FIG. 2 is a schematic representation of an alkylation unit incorporatingthe device shown in FIG. 1;

FIG. 3 is a schematic representation of another alkylation unitincorporating the device shown in FIG. 1 and a device for separating theobtained products;

FIG. 4 is schematic representation of a further alkylation unitincorporating the device shown in FIG. 1 and another device forseparating the obtained products.

It is worth noting that the dimensions and relative proportions of eachof the components of the device and units shown in the accompanyingdrawings do not reflect the invention as it can be reduced to practice.By way of example, the hydrocyclone(s) shown in FIGS. 2 and 3 may be, inpractice, 2 to 4 times larger in size than the device per se. Also shownin a simplified way are the elements of the emulsion chamber of thereactor and of a unit for the introduction of sulfuric acid into saidemulsion chamber. However, such dimensions and proportions are notessential and are actually obvious for any one who would manufacture thedevice or alkylation unit according to the invention.

It is worth noting also that the same reference numerals have been usedthroughout, the following description to identify the same structuralelements, whatever be the illustrated embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The device according to the preferred embodiment of the invention asshown in FIG. 1 includes the following basic units:

-   -   a mixing chamber 1 for mixing isoparaffin with recycled reaction        products;    -   an emulsion chamber 2 comprising a peripheral annular space 4        with a pipe connection 5 for introduction of a sulfuric acid        composition, a mixing area 6, and a system of inlet branch pipes        3 that are parallel to the chamber aids and are designed for        injection of the mixture coming from the mixing chamber, each        pipe 3 being provided with a bell mouth at the outlet;    -   a pre-reaction chamber 7; and    -   a reaction chamber 8.

The units are concatenated as shown in FIG. 1, and they altogether forman adiabatic reactor that can be used for sulfuric acid aviation ofisoparaffin by olefins with jet mixing of the components.

As is shown, all the chambers of the device are coaxial and installedvertically in their operative position with the mixing chamber 1 in thelower part of the device and the reaction chamber 8 on top of it.

The emulsion chamber 2 includes a centrally positioned cylindricalsocket 9 which defines the peripheral annular space 4. The emulsionchamber has a height equal to 20 to 60 times the internal diameter ofthe inlet branch pipes 3 used for the hydrocarbon mixture injection. Anenlargement fitting 10 is joined to the outlet of the chamber 2.

The pre-reaction chamber 7 extends in line on top of the enlargementfitting 10. An olefin feed injection unit 11 is provided at the bottomof the pre-reaction chamber 7. This injection unit comprises injectors12 having their axes running upward at an angle of 0 to 30° with respectto the vertical.

The reaction chamber 8 is separated from the pre-reaction chamber 7 bymeans of a baffle 13 having nozzles 14 mounted therein for providingpassage to the reaction mixture. It comprises a vertical housing 15 anda circulation pipe 16 which is coaxial with the housing and installedwith side clearances relative to the housing to allow recirculation ofthe injected emulsion in a closed circuit. Several connecting pipes 17are tied into the bottom of the housing 15 of the reaction chamber 8 forwithdrawal of the reaction mixture.

Injectors 19 connected to supply pipes 18 are provided for injecting anolefin feed near the top and bottom ends of the circulation pipe 16 andin one or several tiers over the pipe height. These injectors 19 havetheir axes running upward at an angle of 0 to 30° with respect to thevertical. Preferably, each tier provided along the height of thecirculation pipe 16 comprises at least three injectors 19.

The nozzles 14 mounted in the baffle 13 separating the pre-reactionchamber from the reaction chamber are arranged along a circle whosediameter is equal to 0.6 to 0.75 times the inner diameter of thecirculation pipe 16. The inner diameter of the, circulation pipe 16 isequal to 0.55 to 0.75 times the inner diameter of the housing 15 of thereaction chamber.

The height of the circulation pipe is preferably equal to 3 to 9 timesits inner diameter. Preferably also, the sum of the cross-sections ofthe nozzles 14 of the baffle 13 is equal to 0.04 to 0.2 times thecross-section of the circulation pipe.

Advantageously, the reaction chamber 8 is also provided with anadditional axial connecting outlet 20 on its top to allow liquid orvapor emission directly from the reaction chamber whenever requiredduring regular operation of the reactor and/or during preparatory andfinal operations for reactor start-up and shut-down.

FIG. 2 is a simplified flow chart of an example of alkylation unit inwhich incorporating the device according to the preferred embodimentinvention as shown in FIG. 1 can be incorporated.

As can be seen, the unit shown in FIG. 2 incorporates the device shownin FIG. 1, a hydrocyclone 21 connected to the connecting pipes 17 andinjectors 19 of the reaction chamber 8, an acid gas separator 22 and ahydrocarbon gas separator 23 connected to the hydrocyclone 21, a set ofpressure reducing valve 24 and 25 respectively connected to the gasseparators 22 and 23 upstream of the same, and a set of pumps 26 and 27respectively connected to the gas separators downstream of the same.

In use, the isoparaffin used as starting material is cooled down to atemperature lower than +12° C. The so called isoparaffin is fed via aline I into the mixing chamber 1 of the device where recycled reactionproducts cooled down at a temperature lower than +12° C. aresimultaneously injected by the pump 27. The mixture obtained in thechamber 1 is fed in multiple parallel jets through the inlet branchpipes 3 into the emulsion chamber 2 where sulfuric acid is also fed. Thejets are directed through the pipe connection 5 into the peripheralannular space 4 of the emulsion chamber 2. The fine-dispersed emulsionformed in the emulsion chamber 2, exits from the same through theenlargement fitting 10. A given portion of the olefin supplied by theolefin feed injection unit 11 is fed through the nozzles 12 in theemulsion to react with the isoparaffin contained in it. Such a reactionoccurs in the pre-reaction chamber 7. The second emulsion which is soformed, is fed through the nozzles 14 into the reaction chamber 8 whereit is circulated in a closed circuit by means of the circulating pipe16, the housing 15, the baffle 13 and the upper end of the reactor. Abalanced amount of the reaction mixture formed within the reactionchamber 8 is withdrawn through the connecting pipe 17. In several tiersover the height of the reaction chamber, near the inlet and outlet endsof the circulation pipe 16 as well as near the middle part of itsheight, another portion of the olefin feed is injected in jet streamsinto the emulsion through the supply pipes 18 and injectors 19. Afurther portion of the olefin feed also can be injected into thereaction chamber at the outlet of the same.

The reaction mixture exiting the reaction chamber 8 is fed into thehydrocyclone 21 where it is separated into a heavy weight,acid-containing phase and a light weight, hydrocarbon-containing phase.Instead of one hydrocyclone as shown in FIG. 2, use could be made of aset of hydrocyclones that would include several concatenatedhydrocyclones per each phase to be extracted in order to provide arequired level of rectification of every such phase. Such will be betterdisclosed hereinafter with reference to FIG. 3 and FIG. 4.

In use, vapor may be liberated in the hydrocyclone. Therefore, thehydrocyclone is preferably designed in order to provide a vapor exit viaa separate line IV leading to a compressor (not shown). The separatedacid-containing phase is withdrawn from the bottom of the hydrocyclone21 and fed into the gas separator 22 via a pressure reducing valve 24.As a result of throttling in the valve, a given amount of hydrocarbonscontained in the acid is boiled away, thereby cooling off the acid.Vapor formed by boiling is withdrawn from the separator 22 and directedto a compressor (not shown) via the line IV while the pump 26 recyclesthe cooled sulfuric acid composition into the emulsion chamber 2. Agiven amount of waste acid may be withdrawn for regeneration via a lineVI. A corresponding amount of fresh acid may then be fed via a line IIIto compensate it.

The light weight, hydrocarbon-containing phase is fed from thehydrocyclone through a reducing valve 25 into another gas separator 23where vapor separated as a result of throttling is also directed to thecompressor (not shown) via the line. The reaction products cooled due toevaporation of their most easily boiling components, are separated intotwo parts. One part is recycled into the mixing chamber 1 by the pump 27(as recirculated reaction products), while the other part is fed via aline V to an adjacent neutralization, rectification and separation unit(not shown) for the purpose of obtaining the requested baseproduct—alkylate.

Tests carried out by the Applicant have shown that best results areachieved when the amount of sulfuric acid circulating through the deviceaccording to the invention and of the other components of the alkylationunit that are used for separation of the recycled reaction mixtureranges between 40 to 80 m³/t of commercial grade alkylate.

Best results are also achieved when the first emulsion flows at a speedof 1.5 to 3.5 m/s and the second emulsion at a speed of 2 to 4 m/swithin the device.

Best results are further achieved when the pressure drop at the level ofthe nozzles 12 and 19 connected to the olefin feed injection unit 11 andto the supply pipes 18 is higher than 1 kg/cm², and preferably between 1and 4 kg/cm².

Best results are still further achieved when the reaction mixture isintroduced into the hydrocyclone 21 at a speed of 4 to 10 m/s.

Advantageously, sensors (not shown) connected to a control panel may beprovided to check all these parameters and ensure that they fall withinthe above mentioned ranges.

FIG. 3 is a flow chart of another example of an alkylation unitincorporating the device according to the preferred embodiment of theinvention as shown in FIG. 1.

The unit shown in FIG. 3 comprises the device shown in FIG. 1. The unitalso comprises a hydrocyclone 21 connected to the outlet connecting pipe17 of the reaction chamber 8 to separate the reaction mixture into ahydrocarbon-containing phase and an acid-containing phase. The unitfurther comprises a gas separator 28 for removing gas and vapor from thehydrocarbon-containing and acid-containing phases after the same havebeen subjected to a pressure reduction through a set of valves 24 and25. The unit still further comprises pumps 26 and 27 for recycling thereaction products and acid.

The gas separator 28 consists of a horizontal vessel that is divided bya vertical baffle plate 29 into a settling tank 30 and an accumulationtank 31. The setting tank 30 is provided with supply connecting pipes 32and 33 connected to the valves 24 and 25, respectively, through whichthe acid-containing and hydrocarbon-containing phases are separatelyfed. The settling tank is also provided with outlet connecting pipes 34and 35 through which the settled acid and reaction products to berecycled may be extracted. These connecting pipes are connected to thepumps 26 and 27 for recirculation of the reaction products and acid. Thegas separator 28 also comprises a separate connecting pipe 36 fordischarge of spent add for regeneration. This connecting pipe 36 opensinto a compartment formed at the bottom of the settling tank between theoverflow baffle plate 29 and an additional baffle 37 provided at thebottom of the settling tank upstream the baffle plate 29. Such anarrangement allows discharge of a lighter acid-containing phase.

Another outlet connecting pipe 38 is provided in the lower part of theaccumulating tank 31 for allowing withdrawal of liquid reaction productsin liquid form. This connecting pipe 38 is connected to a pump 41 whichdischarges the reaction products for rectification and deisobutanizationin order to extract the requested commercial grade alkylate. As shown,the upper part of the accumulation tank 31 is provided with a knockoutdrum 39 and a further outlet socket 40 for vapor withdrawal to acompressor.

Advantageously, the unit shown in FIG. 3 may also comprise anotheroutlet connecting pipe positioned to allow withdrawal of the reactionproducts for recycling purpose from a level that is lower than theheight of overflow baffle plate. This connecting pipe 42 can be in theform of an horizontal perforated pipe header or collector having an axisparallel to the overflow baffle plate 29 and a height measured from abottom portion of the vessel 28 that is equal to H₁. H₁ is preferably0.5 to 0.8 time the height H of the overflow baffle plate. The header orcollector 42 is located at a distance L from the baffle plate, that ispreferably equal to 0.25 to 1.0 time the height H of said baffle plate.

FIG. 4 is a flow chart of a further example of an alkylation unitincorporating the device according to the preferred embodiment of theinvention as shown in FIG. 1.

The unit shown in FIG. 4 comprises the device shown in FIG. 1. It alsocomprises a hydrocyclone 21 connected to the outlet connecting pipe 17of the reaction chamber 8. It further comprises two other hydrocyclones43 and 44 for sharp separation of the acid-containing phase separatedwithin the hydrocyclone 21, and one further hydrocyclone 45 for sharpseparation of the hydrocarbon-containing phase separated within thehydrocyclone 21. The unit also comprises a cyclone gas separator 46 forprocessing the heavy weight lower flow discharged from the hydrocyclone45, a cyclone gas separator 47 for processing the lightweight upper flowdischarged from the hydrocyclone 45, and a separator 48.

The separator 48 consists of an horizontal vessel that is separated by aset of baffle plates 49, 50 into two opposite liquid hydrocarbonsaccumulating tanks 51 and 52 and a central settling tank. The settlingtank that is formed between the baffles 49 and 50, is also divided by avertical baffle 53 into a settling section 54 for the reaction productsto be recycled, and a settling section 55 for the commercial gradereaction products to be recovered. The lower end of the baffle 53extends at a distance away from the bottom of the vessel 48 while itsupper end extends at 30 to 100 mm above the upper ends of the baffles 49and 50. The bottom portion of the accumulating tank 51 is provided witha connecting pipe 56 for discharge of the reaction products to berecycled while the bottom portion of the accumulating tank 52 isprovided with a connecting pipe 38 for discharge of the commercial gradereaction products.

The setting section 54 for the reaction products to be recycled isconnected by means of outlet connecting pipes 57, 58 to the cyclone gasseparator 46. As shown, the outlet connecting pipe 57 that is used forvapor discharge from the separator 46 extends higher than the upper endof the baffle 49. As also shown, the connecting pipe 58 used forextraction of the liquids from cyclone gas separator 46, extends in thelower part of the separator 48.

The settling section 55 for the commercial grade reaction products to berecovered is connected by means of outlet connecting pipes to thecyclone gas separator 47. As shown, the outlet connecting pipe 59 thatis used for vapor discharge from the separator 47 extends higher thanthe upper end of the baffle 50. As also shown, the connecting pipe 60used for extraction of the liquids from the cyclone gas separator 47extends in the lower part of the settler 48.

As may be seen, the separators 46 and 47 are connected to thecorresponding outlets of the hydrocyclone 45 through a pair of pressurereduction valves 61 and 62.

A connecting pipe 34 is provided at the bottom of the settling section55 for discharging the acid to be recycled. A vortex breaker 63 ismounted above the connecting pipe 34 to exclude funnel formation andhydrocarbon suction into the acid to be recycled. The upper part of eachaccumulating tank is also provided with a knockout drum 39 and aconnecting pipe 40 for vapor discharge to a compressor. Each knockoutdrum 39 is provided with a bottom 63 from which projects a downcornerleg 64, 65 having a lower open end dropping into the lower part of thecorresponding accumulating tank.

The method that may be carried out with the unit shown in FIG. 3 isgenerally similar to the one described earlier. The main difference isthat after discharge from the hydrocyclone 21 and pressure reductionthrough the valves 24 and 25, the acid-containing andhydrocarbon-containing phases obtained from the reaction mixture are fedin the gas separator 28 for complete mixture separation. The separatedvapor is discharged to a compressor through the knockout drum 39 andconnecting pipe 40. A downcorner leg projecting beneath the liquid levelof the settling tank trickles down the liquid separated in the knockoutdrum. In this settling tank, parallel flows of acid and liquidhydrocarbons provides further rectification due to their densitydifference. An acid cooling is also achieved since the layer of reactionproducts which is cooler than the layer of acid, is located above thelayer of acid. As proved by results of tests carried out by theApplicant, the acid temperature at the inlet of the gas separator is2-3° C. higher than the temperature of the hydrocarbons that have beencooled down. Such is due to partly evaporation of isoparaffins bypressure reduction. To sum up, heat exchange efficiency is very high dueto following reasons:

-   -   direct contact of mediums with different temperatures;    -   constant renewal of contact surface due to emergence and        evaporation of reaction products obtaining heat from a warmer        acid located beneath;    -   sinking of acid globules cooled at the contact surface and        replacement thereof with warmer globules emerging from the        bottom.

The reaction products to be recycled are directed by the pump 26 back tothe mixing chamber 1 through the perforated collector 42 and theconnecting pipe 35. The remaining amount of reaction products flows overthe baffle plate into the accumulation tank 31, from which they aredischarged by the pump 41 through the connecting pipe 38 towards arectification and deisobutanization unit (not shown) in order to obtainthe requested commercial grade alkylate.

The sulfuric acid to be recycled is withdrawn from the bottom part ofthe vessel 28 via the connecting pipe 34 and is pumped back forrecycling by the pump 27 as it was described earlier.

As shown in FIG. 3, withdrawal of spent acid for regeneration isprovided via the connecting pipe 36 connected to the compartment formedbetween the overflow baffle plate 29 and the additional baffle 37. Suchallows withdrawal of a lighter phase of the reaction mixture toregeneration.

The alkylation unit shown in FIG. 3 permits to produce a high quality,commercial grade alkylate and to reduce the sulfuric acid consumptiondue to a rapid emulsion separation in the hydrocyclone, an efficientcooling of the acid in the gas separator and an efficient after-settlingprocess of the commercial grade reaction products that provides minimumcarry-over of acid particles to the accumulating and roll-out areas.

However, the way of carrying out the method according to the inventionis not limited to the flow chart given as example only in FIG. 3. As amatter of fact, FIG. 4 shows another possible way of carrying out themethod according to the invention for sulfuric acid alkylation ofisoparaffins by olefins.

Like in the examples shown in FIGS. 2 and 3, the hydrocyclone 21 of theunit shown in FIG. 4 is used to separate the reaction mixture into ahydrocarbon-containing phase and an acid-containing phase. Such aseparation suspends further chemical conversion in the emulsion and setsthe composition of the reaction products. However, unlike the earlierexamples, the hydrocarbon-containing phase separated within thehydrocyclone 21 is subjected to another separation into an upperlightweight flow and a bottom heavy weight flow within the otherhydrocyclone 45 that is located downstream. The upper lightweight flowexiting from the upper outlet of the hydrocyclone 45 qualifies ascommercial grade reaction products and is fed via the pressure reductionvalve 62 and the gas separator 47, to the settling section 55 of thevessel 48. The vapor phase at the upper outlet of the gas separator 47exits above the level of the overflow baffle plate 50 that determinesthe liquid level in the vessel. The liquid phase separated within thegas separator 47 exits from the same below that level, e.g. beneath theliquid layer. The bottom heavy weight flow exiting from the bottomoutlet of the hydrocyclone 45 forms the reaction products to be recycledand is fed via the pressure reduction valve 61 and the gas separator 46to the other settling section 54 of the vessel 48. Vapor and liquidphases exiting the gas separator 46 are fed into the section 54 atheights similar to what has been described earlier.

The acid-containing phase collected at the bottom of the hydrocyclone 21is separated within the hydrocyclone 43 into an upper lightweight flowand a bottom heavy weight flow. The upper flow that is enriched byhydrocarbons is fed to the settling tank of the vessel 48, preferably tothe settling section 54, as reaction products to be recycled. The bottomheavy weight flow exiting from the hydrocyclone 43 is fed to a furtherhydrocyclone, viz. the one numbered 44, for further separation. Theheavy weight layer exiting from the bottom of hydrocyclone 44 is fed tothe settling section 54 of the vessel 48 for further utilization asrecycled acid, along with the upper lightweight flow exiting from thehydrocyclone 43. The upper lightweight flow exiting from thehydrocyclone 44 is discharged from the unit as waste acid.

Several settling areas are formed within the vessel 48. The vapor flowsare collected above the level of the overflow baffle plates 49 and 50Some of these vapors come from the gas separators 46 and 47. Othervapors come from isobutane evaporation in the settling sections 54 and55 due to the heat exchange between the hydrocarbons and the lowerwarmer layer of acid. All these vapors are withdrawn via the knockoutdrums 39 and connecting pipes 40 located above each of the accumulatingtanks 51 and 52. The vapors are then directed to a compressor forcompression, condensation, cooling and return to recycling as one of theportions of recycled isobutane. Reaction products to be recycled arecollected in the settling tank 54 formed between the baffles 49 and 53.As the level of baffle 49 is 30 to 100 mm lower than the level of baffle53, the reaction products that reach the top edge of the baffle 49,spill over it into the accumulating tank 51, from where they are pumpedvia the connecting pipe 56 and the pump 27 back to the reactor. Prior toreaching the settling section 55, the liquid reaction products fedtherein are subjected to a two-stage acid separation in thehydrocyclones 21 and 45. Therefore, they practically do not contain anymore acid particles. Thus, upon spilling over the baffle 50 into theaccumulating tank 52, they can be pumped via the connecting pipe 38 andpump 41 for further treatment, where they require significantly lessrectification efforts.

Sulfuric acid which forms the heaviest flow, is collected in the bottompart of the vessel 48. The so collected acid is completelydecontaminated (degased) and cooled. The acid may freely flow under thebaffle 53 since the bottom end of this baffle 53 is spaced apart fromthe bottom of the vessel. In the embodiment shown in FIG. 4, heatexchange between the acid and hydrocarbons is intensified due to theintroduction of the acid into the layer of hydrocarbons and vice versa.In the embodiment shown in FIG. 4, acid is also withdrawn via the hood63 with a crosspiece mounted over the connecting pipe 34. This featureeliminates funnel formation and suction by acid flow, of hydrocarbonslocated under the acid layer.

EXAMPLE

Tests to check the efficiency of the method according to the inventionwere carried out in a pilot unit having a structure similar to the oneshown in FIG. 3 and the following particulars:

diameter of the emulsion chamber 2: 300 mm diameter of the reactionchamber 15: 700 mm number of nozzles 12: 3 number of nozzles 19: 9amount of H₂SO₄ circulated through the device: 50 m³/per ton of alkylatefirst emulsion flow rate: 2.55 m/s second emulsion flow rate: 3.6 m/solefin injection pressure drop: 2.5 kg-force/cm²

During the tests, isobutane was fed into the device after having beencooled down to a temperature of +3.8° C. Recycled reaction products werealso fed into the device after having been separated from the sulfuricacid and then cooled down to a temperature of +3.2° C. A mixture ofhydrocarbons was fed to the emulsion chamber of the reactor in multipleparapet jets. Sulfuric acid circulating in the system and separated fromthe reaction products was fed in the peripheral annular space of thereactor beneath the diffuser of the emulsion chamber. Then, 27% of thetotal olefin feed was injected in wakes through the nozzles 12 into soprepared emulsion of hydrocarbons in sulfuric add. The olefin feedrepresented a mixture of incoming butane-butylenes fraction and somepart of internally recycled isobutane. The composition of the olefinfeed was as follows:

components rest of the compo- C₃H₈ C₃H₆ i-C₄H₁₀ n-C₄H₁₀ Σ C₄H₈ i-C₅H₁₂nents % vol. 1.1 0.1 74.3 8.3 15.9 0.2 0.1

An interaction process of olefins (essentially butylenes) contained inthe feed with isobutane took place in the pre-reaction chamber 7 abovethe nozzles 12. Such a process was also continued through the nozzles 14mounted on the baffle that separates the pre-reaction chamber 7 from thereaction chamber 8.

The injectors 19 for the injection of the balance of the olefin feedwere arranged below the low end of the circulation pipe 16 and in twotiers over its height. All the balance of the feed was injected throughthe injectors 19 into the emulsion. The so-obtained reaction mixture wasremoved from the reactor through three connecting pipes located at thebottom part of the reaction chamber, and it was directed to thehydrocyclone 21 for separation. The reaction mixture temperature at theoutlet of the reactor was +6.5° C. Initial separation of the reactionmixture from the reactor was provided in the hydrocyclone at a rate atsupply pipe of 4.7 m/s. Final separation after pressure reduction wasobtained in the horizontal separator vessel divided into one settlingtank and one accumulating tank.

After separation, part of the reaction products was directed for an acidand alkali wash with a further isolation of alkylate while the otherpart was recycled through the device.

After separation from the hydrocarbons and cooling, the acid wasrecycled in the unit with a discharge of part of the waste acid and areplenishment of a make-up (fresh) acid, in such a way that the averagestrength of the recycled acid mixture was maintained at 91-92%.

The so obtained alkylate has the following characteristics:

Results of ASTM D-86 Single Stage Laboratory Distillation

Boil-off Initial boiling 10% 50% 90% End boiling MON Temperature 37 64108 149 195 93* in ° C. *octane number

Of course, numerous modifications could be made to the device and unitsdisclosed hereinafter without departing from the scope of the invention.

1. A device for mixing and reacting at least two liquid components,comprising: (a) a mixing chamber for preparing a mixture of two of saidcomponents; (b) an emulsion chamber for preparing a first emulsion,where the mixture prepared in the mixing chamber (a) is injected inmultiple parallel jets; (c) a pre-reaction chamber for preparing asecond emulsion, where a given portion of one of said components isinjected in jet streams into the first emulsion coming from the emulsionchamber (b); and (d) a reaction chamber of given height andcross-section where the second emulsion coming from the pre-reactionchamber (c) is injected through nozzles and one of said components isinjected in jet streams all over the cross-section and height of saidreaction chamber, said reaction chamber being devised so that saidsecond emulsion is circulated in a closed circuit and comprising anoutlet through which a balanced amount of reaction mixture iscontinuously discharged; wherein said mixing chamber (a), emulsionchamber (b), pre-reaction chamber (c) and reaction chamber (d) arecoaxially arranged one above the other in vertical position andaltogether form a reactor with said mixing chamber (a) being located atthe bottom of the reactor and said reaction chamber (d) on top thereof.2. The device of claim 1, wherein the emulsion chamber (b) includes: aplurality of parallel inlet branch pipes having a given internaldiameter, through which the mixture prepared in the mixing chamber (a)is injected; a cylindrical socket centrally mounted within said emulsionchamber, said socket having a height equal to 20 to 60 times to internaldiameter of the parallel inlet branch pipes, said socket also having anupper outlet; and an enlargement fitting joined to the upper outlet ofsaid cylindrical socket.
 3. The device of claim 1, wherein thepre-reaction chamber (c) has a bottom portion provided with a feedinjection unit comprising injectors having axes running upward at anangle of 0 to 30° with respect to the vertical.
 4. The device of claim1, wherein: the reaction chamber (d) is separated from the pre-reactionchamber (c) by means of a baffle with nozzles mounted therein forallowing injection of the second emulsion; and said reaction chamber (d)comprises a vertical housing and a circulation pipe which is coaxialwith said housing and installed with side clearances relative to saidhousing.
 5. The device of claim 4, wherein the housing of the reactionchamber (d) has a bottom with at least two connecting pipes tied to itfor withdrawal of the reaction mixture.
 6. The device of claim 4,wherein the circulation pipe has a top, a bottom and a given height, andother injectors are arranged near said top, said bottom and over saidheight in the form of tiers for injection of another feed, said othernozzles having axes running upwards at an angle of 0 to 30° with respectto the vertical.
 7. The device of claim 6, wherein each of said tierscomprises at least three injectors.
 8. The device of claim 4, whereinthe nozzles in the baffle separating the pre-reaction chamber (c) fromthe reaction chamber (d) are arranged along a circle having a diameterthat is equal 0.6 to 0.75 the inner diameter of the circulation pipe. 9.The device of claim 4, wherein the circulation pipe has an innerdiameter which is equal to 0.55 to 0.75 times the inner diameter of thehousing of the reaction chamber (d).
 10. The device of claim 4, whereinthe circulation pipe has a height and an inner diameter whose ratio isranging from 3 to
 9. 11. The device of claim 4, wherein the nozzles ofthe baffle have inner diameters with cross-section whose total is equalto 0.04 to 0.2 times the cross-section of the circulation pipe.
 12. Thedevice of claim 1, wherein the reaction chamber (d) is also providedwith a top axial connecting outlet.
 13. A device for separating areaction mixture containing immiscible liquids of different densitiesand some gas or vapor, wherein said device comprises a horizontal vesselincorporating: (a) at least one vertical overflow baffle plate thatextends within said vessel and divides it into at least one settlingtank and one accumulation tank; (b) supply connecting pipes forintroducing streams of said reaction mixture into the settling tank; (c)outlet connecting pipes for discharging the liquid having the highestdensity from a bottom portion of the settling tank; (d) other outletconnecting pipes for discharging liquids of lower densities from thesettling tank and the accumulation tank, wherein at least one of saidother connecting pipes is positioned in another bottom portion thesettling tank; and (e) at least one further outlet connecting pipe fordischarging gas or vapor from an upper part of the vessel.
 14. Thedevice of claim 13, wherein one of said other connecting pipes fordischarging liquids of lower density is in the form of a perforated pipeheader having an axis parallel to the overflow baffle plate, said pipeextending upwards from the bottom portion of the settling tank at alower height than the overflow baffle plate.